Compounded mineral oil compositions containing amine salts of di oxo-octyl acid orthophosphates



fifimfiii Patented Feb. 26, 1963 CQMPQUNDED MWERAL Oil. COMEOSITIONSCONTAE'NENG AMENE SALTS GE Di X0-0TYL AQID ORTHOPHSSPHATES Troy L.Cantrell, Drexel Hill, Pa., and lohn G. Peters, Audubon, Ni, assignorsto Gulf 0i} orporation, Pittsburgh, Pa., a corporation oi PennsylvaniaNo Drawing. Original application May 9, 1955, Ser. No. 507,128, newPatent No. 2363904, dated Dec. 9, 1958. Divided and this applicationJune. 17, 1958, Ser. No. 742,494

5 Claims. (Cl. 252-325) This invention relates to novel compoundedmineral oil compositions containing amine salts of dialkylorthophosphates. More particularly, the invention relates to suchmineral oil compositions that contain substantially neutral salts of Cprimary n-alkyl amines and di oxo-octyl acid orthophosphates.

In order to protect metal surfaces contacted by mineral oil compositionsfrom rust or corrosion, it is desirable that such compositions haveincorporated therein a material having rust and corrosion inhibitingproperties. In order that the rust inhibiting potency of the oils maynot be diminished during storage, transporting, or use, it is importantthat the inhibitor employed in the oil should not be susceptible towater leaching. In this connection, it is noted that mineral oils of thefuel and lubricant type may be exposed to contact with water in bulkstorage tanks, in tanks of marine vessels, or during usage in thepresence of water, steam, or atmospheric moisture.

We have found .that the substantially neutral salts of primary n-alkylamines containing 8 to 18 carbon atoms per molecule and di oxo-octylacid orthophosphate impart excellent rust and corrosion inhibitingcharacteristics and other desirable characteristics as hereinafterdiscussed to various mineral oil compositions, and at the same time theyare extraordinarily resistant to water leaching. The present inventionincludes various mineral oil compositions containing minor amounts ofsuch salts. The salts themselves are described and claimed in ourcopending application Serial No. 507,128, filed May 9, 1955, now PatentNo. 2,863,904. This application is a division of our copendingapplication.

The compounds whose use is included by the present invention can beprepared in any suitable manner. According to a preferred procedure, asdescribed in our copending application, above-identified, a di oxo-octylacid orthophosphate is substantially neutralized by addition thereto ofan approximately equimolar amount of a primary n-alkyl amine of theclass disclosed herein. The reaction proceeds spontaneously at roomtemperature with evolution of heat. The temperature of the reactionshould be maintained below about 200 F. and preferably below about 180F., in order to prevent water from splitting out of the addition saltreaction product. Control of the reaction temperature may be achieved,for example, by controlling the rate of addition of n-a kyl amine, or byexternal cooling, or both. The overall time required to complete thereaction will vary somewhat according to the method by which thetemperature is controlled and according to the temperature at which thereaction is carried out. Normally, it will be desirable to continue tostir the reaction mixture after amine addition is complete for about thesame length of time as required to add the amine, in order to insurecompletion of the reaction. Toward the end of the addition of the amine,it may be found convenient to measure the pH in order to insure that thereaction product will be substantially neutral, i.e., that it will havea pH of about 5.5 to about 7.5, and preferably about 7.

The di oxo-octyl ester of orthophosphoric acid used in making the aminesalts whose use is included by this invention also may be prepared inany suitable manner. For example, a preferred method involves additionof P 0 to the oxo-octyl alcohol in a mol ratio of about 1:4, againmaintaining the reaction temperature below about F. by controlling therate of addition of P 0 or by external cooling, or by both. Afteraddition of P 0 is' complete, the reaction mixture should be stirreduntil the product is clear. Some external heating, below about 180 B,may be desirable toward the end of the reaction in order to acceleratecompletion.

Amines that form suitable addition salts With the disclosed di oxo-octylphosphates are primary n-alkyl amines containing 8 to 18 carbon atomsper molecule. An :example of a preferred primary n-alkyl amine thatforms suitable salts with the di oxo-octyl acid orthophosphate isn-dodecyl (lauryl) amine. It is not necessary that the amine be in pureform, and other amines can be present. In fact, excellent results havebeen obtained with addition salts prepared from mixtures of primaryn-alkyl amines of the class disclosed. An example of a commercialmixture of amines that forms outstandingly effective addition salts withdi oxo-octyl acid orthophosphate is cocoamine, which is a mixture ofprimary n-alkyl amines derived from coconut oil fatty acids. Cocoaminenormally has a mol combining weight of about 210, a melting point ofabout 21 C., and is composed principally of n-dodecyl amine, togetherwith lesser amounts of homologous, primary straight chain aminescontaining an even number of carbon atoms ranging from 8 to. 18.

Examples of other amines within the disclosed class are n-octyl amine(caprylyl amine), n-decyl amine (capryl amine), n-tetradecyl amine(myristyl amine), and n-hexadecyl amine (palmityl amine).

Dioctyl acid orthophosphates that are suitable for the purposes of thisinvention are those derived from socalled oxooctyl alcohols, which, asis known, are highly branched chain saturated aliphatic monohydric octylalcohols prepared by the 0x0 process. Briefly, this process involves thehydroformylation of olefinic hydrocarbons, followed by hydrogenation ofthe car bonylic compounds thus obtained. Normally, the olefinichydrocarbons used in the manufacture of oxo-octyl alcohols are preparedby condensation of C and C olefins in the usual proportion in which theyoccur in refinery process gases. In this case, oxo-octyl alcoholsnormally will contain a mixture of branched chain isomers of octylalcohol, and the mixture will consist mostly of isomericdimethylhexanols. Although the above-indicated composition is the mostcommon for oxo-octyl alcohols, it will be appreciated that the natureand propertions of the isomeric mixed alcohols can be varied to someextent by varying the proportions of the C and C olefms used inpreparing the C olefin to be hydroformylated.

Although dialkyl acid orthophosphates prepared from any oxo-octylalcohols can be used to form the n-alkyl amine salts of this invention,We prefer to use those prepared by hydroformylation and hydrogenation ofa mixed 0, olefin that is obtained by condensing C and C olefins in theproportion that they normally occur in petroleum refinery gases; thatis, in the proportion that they occur in the refining, e.g., catalyticcracking, and the like, of heavier petroleum hydrocarbons. Thispreference is based principally on cost considerations.

A specific example of an especially effective agent for the purposes ofthe invention is the neutral addition salt (pl-I 7) of cocoamine and dioxo-octyl acid orthophosphate. Other salts included by the invention arethe substantially neutral n-octyl amine, n-decyl amine, n-tetradecylamine, and n-hexadecy-l amine salts of di oxo-octyl acid orthophosphate.

By way of further illustrating the preparation of salts Whose use isincluded by this invention, in a specific instance, to 2600 g. ofoxo-octyl alcohol, which had been previously placed in a stainless steelvessel set in a water bath, were slowly added 710 g. of phosphoruspentoxide, with stirring, the temperature of the reaction beingmaintained at 180 F. or below. Stirring of the reaction mixture wascontinued until the product became elem. The reaction was consideredcomplete after about 3060 minutes.

The oxo-octyl alcohol used in the reaction was obtained by thehydrogenation of a hydroformylated mixture of heptene isomers. Theoxo-octyl alcohols had the structure where R and R are hydrogen oralkyl. The alcohols had the following inspections:

Specific gravity, 20/20 C 0.8324 Viscosity, kinematic, cs., 20 C. 12.43Refractive index, n /D 1.4313 C alcohol content, percent by wt. 99.3 Ccarbonyl content, percent by wt. 0.06 Distillation, isooctyl alcohol,ASTM D107849T, C.

Over point 184.0 Dry point 188.5 10% 185.5 50% 186.4 90% 187.5

The product of the foregoing reaction Was di oxo-octyl acidorthephosphate. To 300 g. of this product there were added 223 g. ofcocoamine (Armeen CD, Armour & Co.), with stirring, the temperature ofthe reaction being maintained below about 180 F. The addition of theamine was complete in about 10-15 minutes and stirring of the mixturewas continued for about an equal length of time thereafter. The productof this reaction was the cocoamine salt (principally ndodecyl aminesalt) of di oxo-octyl acid o-rthophosphate. This product had thefollowing inspections:

Gravity, API 21.2. Viscosity, SUV, sec., 210 F. 403. Color, NPA 1.25.Appearance Bright. Physical state, room temp. Liquid. Phosphorus,percent 5.62. pH value (glass calomel electrodes) 7.2.

The salts whose use is included by this invention can be incorporated invarious mineral oil compositions in amounts sufiicient to impartcorrosion inhibiting properties to the composition. For example, thesalts of this invention are useful when employed in oils in amounts ofabout 0.001 to about 1.0 percent by weight. Excellent results have beenobtained by the use in petroleum distillates such as gasoline, jetengine fuel and lubricating oil, of amounts of the salts between about0.002 and about 0.1 percent by weight of the composition. It will beunderstood that the optimum amount will vary according to the particularmineral oil and according to the conditions to which the oil issubjected.

Mineral oil compositions included by the invention are illustrated bythe following examples:

EXAMPLE I A composition according to this invention was prepared bydissolving 0.0126 percent by weight of the salt prepared as describedabove in a highly par-afiinic turbine lubricating oil base that had notbeen previously inhibited against rust. This oil composition was testedaccording to the standard accelerated corrosion test, ASTM D665- 53T,Procedure A (distilled water). After 24 hours, the standard steel testrod was bright and free from rust. In contrast, the uninhibited base oilwill produce 100% rusting under the same test conditions.

EXAMPLE II Other compositions were prepared according to this inventionby incorporation of a neutral salt of coeoamine and di oxo-octylo-phosphate referred to in Example I, in amounts of 5 and 20 pounds perthousand barrels of fuel, into separate samples of a military grade JP-4jet engine fuel that was otherwise uninhibited against rusting, and thathad been previously depolarized with activated alumina. Thesecompositions were tested by subjecting them to a modification (MILI25017(ASG) Method 4011-13) of ASTM 13665-531", procedure B (salt water),wherein the composition is first subjected to Water washing with 10% ofdistilled water, and then subjected to the ASTM test procedure, modifiedto 100 F. and 20 hours, for fuel. At the end of the 20 hour period, thetest rods from both samples were free of rust. The uninhibited,depolarized base fuel will produce essentially complete rusting underthe same circumstances.

EXAMPLE III Another composition was prepared in accordance with thisinvention by incorporating 16 pounds per thousand barrels of the salt ofExample H in a commercial /87 grade aviation gasoline containing 0.5 ml.tetraethyllead per gallon. This composition was tested according to amodified ASTM D66553T, wherein the gasoline, previously depolarized withg./ gal. of activated alumina, was subjected to procedure A of the ASTMtest, modified to 80 F. and 20 hours for fuel. At the end of the testperiod, the steel test rod showed no rust. The uninhibited gasoline willproduce 100 percent rusting of the test rod under the same testconditions.

The foregoing examples demonstrate the effectiveness of the n-alkyl dioxo-octyl orthophosphates of this inventionin a variety of mineral oilcompositions. It will be appreciated that these examples areillustrative only and that other mineral oil compositions havingcorrosion inhibiting properties and falling Within the scope of theinvention can be prepared by substitution of other n-alkyl amine dioxo-octyl orthophosphates and mineral oils disclosed herein for those ofthe foregoing examples, in the same or equivalent proportions.

The extraordinary resistance to water leaching by the n-alkyl aminesalts of the present invention has been demonstrated by repeated waterwashing of samples of depolarized isooctane containing equivalentamounts of various n-alkyl amine dialkyl orthophosphates and determiningthe amount of the addition salt remaining in the isooctane layer. Moreparticularly, separate samples of depolarized isooctane were made up, onan equivalent phosphorus basis, and containing, respectively, theneutral cocoamine salts of (a) diisoamyl acid orthophosphate, (b)3-methylbutyl, 2-ethylhexyl acid orthophosphate, and

() di oxo-octyl acid orthophosphate. Each sample was washed five timeswith 10 percent by volume of distilled water, and after each wash thewater layer was analyzed to determine the amount of phosphorus therein.From this value the quantity of additive remaining in the isooctanelayer was determined. The results of these tests are presented in thefollowing table:

Table A Hake-up, Percent by Vol;

Depolarized Isooctane Additive Added- Gocoamine Diisoamyl OrthophosphateCocoamine 3-Methylbutyl, 2-Ethylhexyl Orthophosphate COChOAtIDiJJB DiOxo-oetyl Orthophosn-pq Additive m Isooctane, Percent.--

From the foregoing data it will be seen that the additive prepared fromoxo-octyl alcohol was remarkably more resistant to water washing thanthe non-oxo-alcohol derived counterparts. This is quite surprising inview of the highly branched character of oxo-octyl alcohols.

It is noted that the difference in solubility cannot be accounted for onthe basis of molecular weight alone. Thus, the normal plot of watersolubility against the number of carbon atoms in a related series ofcompounds is a concave curve. by a plot of total water soluble materialafter water washes against the number of carbon atoms in the alkylgroups of the phosphate radicals in the compounds of Runs 1 and 2 inaccordance with the normal shape of such curves, indicates that asubstantially larger total number of alkyl carbon atoms would berequired to achieve the low water solubility of the herein disclosedn-alkyl di oxo-octyl orthophosphates. Low water solubility with a lowtotal number of carbon atoms in the alkyl groups of the phosphateradical is important in order not to sacrifice rust and corrosioninhibiting potency.

In addition to the mineral oils disclosed above, the salts of thisinvention will produce good results when incorporated in othergasolines, lubricating oils, kerosene, diesel fuels, furnace oils,grease compositions, synthetic lubricants, and the like. In addition tothe properties previously indicated herein, the compounds of thisinvention are considered to possess preignition control characteristics,antistalling, combustion improving, and tetraethyllead stabilizingproperties,

Extrapolation of the curve produced in addition to the agents disclosedherein, the mineral oil compositions of this invention can have addedthereto one or more additional agents designed to improved one or moreproperties of the composition. Thus, there can be added other anti-rustagents, de-icing agents, detergents, dispersants, antiknock agents, leadscavengers, sludge inhibitors, pour point depressants, ignition controlagents, anti-oxidants, thickeners, viscosity index improvers, and thelike.

As will he apparent from the present context, the ex pression mineraloil is used in a conventional sense to include various hydrocarbon oilcompositions such as gasoline, lubricating oil, kerosene, diesel fuel,and the like.

Many modifications of the above-described subject matter can be resortedto without departing from the spirit or scope of the invention.Accordingly, only such limitations should be imposed thereon as arefound in the appended claims.

We claim:

1. A mineral oil composition comprising a major amount of a mineral oiland a minor amount, sufiicient to impart rust inhibiting characteristicsto the composition, of a substantially neutral salt of a primary n-alkylamine containing 8 to 18 carbon atoms per molecule and di oxo-octyl acidorthophosphate.

2. The mineral oil composition of claim 1, wherein said minor amount isabout 0.001 to about 1.0 percent by Weight of the composition.

3. A lubricant composition comprising a major amount of a lubricatingoil and a minor amount, suiiicient to impart rust inhibitingcharacteristics to the composition, of the substantially neutral salt ofcocoamine and di 0X0- octyl acid orthophosphate.

4. A gasoline composition comprising a major amount of a hydrocarbonmixture boiling in the gasoline range and a minor amount, sufiicient toimpart rust inhibiting characteristics to the composition, of thesubstantially neutral salt of cocoamine and di oxo-octyl acidorthophosphate.

5. A fuel composition for jet engines comprising a major amount of ahydrocarbon mixture boiling in the jet fuel range and a minor amount,sufficient to impart rust inhibiting characteristics to the composition,of the substantially neutral salt of cocoamine and di oxo-octyl acidorthophosphate.

References Cited in the file of this patent UNITED STATES PATENTS2,080,299 Benning et al. May 11, 1937 2,371,851 Smith et al Mar. 20,1945 2,728,643 Vaughn Dec. 27, 1955 2,773,032 Cantrell et al. Dec. 4,1956 2,786,028 Gottshall et a1 Mar. 19, 1957 2,791,495 Rudel May 7, 19572,841,126 Cantrell et al July 1, 1958 2,857,334 Thompson Oct. 21, 19512,863,742 Cantrell et al. Dec. 9, 1958 2,863,745 Cantrell et al Dec. 9,1958 2,863,746 Cantrell et a1. Dec. 9, 1958 2,863,747 Cantrell et al.Dec. 9, 1958 2,863,904 Cantrell et al. Dec. 9, 1958 2,905,542 Gottshallet al. Sept. 22, 1959

3. A LUBRICANT COMPOSITION COMPRISING A MAJOR AMOUNT OF A LUBRICATINGOIL AND A MINOR AMOUNT, SUFFICIENT TO IMPART RUST INHIBITINGCHARACTERISTIC TO THE COMPOSITION, OF THE SUBSTANTIALLY NEUTRAL SALT OFCOCAMINE AND DI OXOOCTYL ACID ORTHOPHOSPHATE.